Why do self-driving cars force a society to answer trolley-problem questions in advance?
Because unavoidable accidents will still happen, and an autonomous car's behaviour in one is fixed by its programming — so the decision has to be taken before the situation arises, not in it.
The argument, set out by Alexander Hevelke and Julian Nida-Rümelin in their 2015 paper on offsetting human lives in unavoidable accidents, runs in three steps:
- In ordinary driving, situations arise in which an accident involving personal injury has already become unavoidable — no available manoeuvre prevents someone getting hurt.
- Fully autonomous cars, if they are ever licensed for public roads, will not be able to avoid such situations either. Better sensors and reflexes shrink the set; they do not empty it.
- Therefore it must be decided in advance which maxims the car's behaviour should follow in them — because the car will do whatever it was built to do, and someone chose that.
The candidate solution the paper examines is a programming that, in an unavoidable accident, weighs potential victims against one another so as to minimise the number and severity of the expected injuries — the "injury-minimising" (verletzungsminimierend) approach.
The central themes that follow from it are the ones the rest of this topic works through: who is the decision-maker, the danger of instrumentalising the victims, the danger of systematically raising the risk for particular groups, the creation of perverse incentives, and questions of fairness.
Go deeper:
TED-Ed: The ethical dilemma of self-driving cars (Patrick Lin) — four minutes that set up exactly this problem, including why the decision has to be made in advance.
Ethics Commission: Automated and Connected Driving (Germany, 2017) — the twenty rules a national ethics commission actually wrote for this question (English PDF).- Wikipedia: Self-driving car — the technology and its regulation, for the state of the world the argument assumes.